The accusation came in a five-page letter released by Botha in response to a letter from the Rev. Frank Chikane, general secretary of the South African Council of Churches, who defended the clergy's growing role in anti-government protest.

The exchange of letters is the latest round of a bitter church-state confrontation that began last month when the government banned all activities by 17 major anti-apartheid organizations. Chikane, Anglican Archbishop Desmond Tutu and other clegymen vowed to fill the void created by the bannings.

On Feb. 29, Chikane, Tutu and 23 other church leaders were arrested while trying to march to Parliament with a petition protesting the crackdown.

Chikane, in a letter to Botha a week ago, defended the clergymen's decision to protest against ''ungodly acts of oppression.''

Botha, in his response, described himself as a devout Christian. He said his government, which denies the black majority a vote in national affairs, strove to broaden democracy and remove discriminatory laws.

Referring to the outlawed African National Congress and South African Communist Party, Botha said to Chikane: ''You love and praise the ANC-SACP, with its Marxist and atheistic ideology, landmines, bombs and necklaces perpetrating the most horrendous atrocities imaginable, and you embrace and participate in their call for violence, hatred, sanctions, insurrection and revolution.

''In the name of God,'' added Botha, ''I call upon you to be messengers of the true Christian religion and not of Marxism or atheism.''

''Necklacing'' is a form of execution in which a gasoline-soaked tire is placed around a victim's neck and set alight. In nationwide unrest from 1984 through 1986, many blacks suspected of collaborating with the government were necklaced by black militants.

The ANC, which wages a bombing and sabotage campaign aimed at undermining white-minority rule, repudiated necklacing last year and the method has been used infrequently in recent months.

At an emergency meeting Tuesday, Anglican bishops from across South Africa pledged support for Tutu in his confrontation with Botha. The bishops said they rejected the president's efforts to depict the dispute as a choice between Marxism and the government's programs.